The long range goal for this project is to determine how hepatotoxic and carcinogenic agents modify the carbohydrate metabolism of rat liver. A necessary control has been the study of the effects of regeneration after a 70% partial hepatectomy. In the next portion of the project period I plan to study further the apparent conversion of the hepatic adrenergic receptor from an alpha-type to a beta-type which occurs one day after partial hepatectomy. Associated with this change is an enhancement of the cellular response to isoproterenol. The measurements to be made include the activities of phosphorylase and cyclic-AMP-dependent protein kinase, the concentration of cyclic-AMP, and a estimation of the number of alpha- and beta-receptors in membranes from livers of sham-operated and partially hepatectomized rats. Studies following the same general approach will be done with cells isolated from livers of rats fed 0.05% alpha-acetylaminofluorene for 1, 2 or 4 weeks to determine whether this state preneoplastic also changes the responsiveness of the hepatic adrenergic receptor.